Describe the levels of organisation in the human body, naming the main body systems.
Analyse the structure of an organ explaining how the different tissues contribute to effective function.
Explain the role of the key components of a balanced diet.
Evaluate the effects of three nutritional deficiencies on health.
Describe how carbohydrates, fats and proteins are broken down physically and chemically.
Analyse the problems associated with protein digestion and explain the importance of enzyme activation.
Explain the mechanisms by which the liver and the kidney retain glucose but eliminate urea.
With reference to the digestive system:
(a)explain how reflexes contribute to the co-ordination of the system,
(b) compare the role of the nervous system with that of hormones in the co-ordination of the system.
Explain the regulation of blood glucose levels using negative feedback mechanisms.
There are six levels of organization in the human body(Matusiak, 2013). These are:
Chemical level – the tiniest building blocks which make up a matter such as the atoms which form molecules by combining with each other.
Cellular level – the smallest unit of any living matter i.e. the cell makes up the cellular level.
Tissue level – similar cells which combine together and perform the same task consist of the tissue level.
Organ level – when two or more different types of tissue perform a particular function, those form an organ.
Organ system level – in this type of organizational leveltwo or more organs perform a similar task.
Organismal level – all the structural levels work together and form the organismal level.
The figure shows the digestive system. The function of the digestive system is to obtain the energy and necessary nutrients and chemicals from the food we intake.
The skeletal system, which consists of 206 bones (270 in newborns), and a network of tendons, ligaments and cartilages, which connects the bones(Haywood, 2009). The skeletal system can be divided into two parts, axial skeleton consisting of 80 bones which helps human maintain their upright posture and appendicular skeleton which has a total of 126 bones and protects the organs and helps with our movements.
The body system in the figure is respiratory system which is serves the following function:
Pulmonary ventilation i.e. inhalation and exhalation (AN, 2012).
Exchanging gases between the bloodstream and the lungs.
Exchanging of gases between the body tissues and the bloodstream through internal respiration.
Creation of sound by vibrating the vocal cords.
Areolar connective tissue – this tissue consists of the blood capillaries which supply nutrients and oxygen to the tissues(Thibodeau, Patton & Anthony, 2012).
Cardiac muscle tissue – the ventricles and atria are contracted by this tissue.
Maintenance of posture.
Joint stabilization.
Generation of heat as a by-product of contraction.
They connect or bind all types of tissues together and hence support the body.
A mechanical framework is provided in the form of a skeleton thus, performing an important function of locomotion(Woodson, 2003).
The intake of food which contains all the required nutrients in a correct proportion is known as a balanced diet (Veitch, 2012).
|
Food examples |
What is a serve |
Daily servings |
|
Bread |
2 slices |
5 to 9 serves each day |
|
Rolls |
1 roll |
|
|
Cereals |
1 cup |
|
|
Wheat biscuit |
1 |
|
|
Pasta |
1 cup |
|
|
Rice |
1 cup |
|
|
Cooked veggies |
½ cup |
4 to 5 serves each day |
|
Medium potato |
½ cup |
|
|
Sliced carrot |
½ cup |
|
|
Broccoli |
½ cup |
|
|
Spinach |
½ cup |
|
|
Cauliflower |
½ cup |
|
|
Salad |
1 cup |
2 to 3 serves each day |
|
Any fruit |
1 piece |
|
|
Fruit juice |
Small glass |
|
|
Raisins |
1-2 tbsps |
|
|
Dried fruits |
4 pieces |
|
|
Milk |
250 ml |
2 to 4 serves each day |
|
Yogurt |
200 g |
|
|
Cheese |
40 g |
|
|
Custard |
250 ml |
Supports energy.
Protects the heart.
Appropriate levels of vitamin B12 help the bones to remain strong and healthy.
Nerve damage is prevented.
The outlook and mood of a person is also improved by it.
Vitamin B12 supports the health of DNA and hence, helps in maintaining a fresh and young look.
Maintaining the health of heart.
Management of weight.
Maintenance of the immune system.
Keeping the mental health intact.
Shortness of breath.
Headache and dizziness.
Coldness in the feet and hands.
Pale skin.
Chest pain.
Peripheral neuropathy.
Fractures of bones.
Permanent bone deformities.
Low calcium levels in the blood hence, leading to seizures, breathing problem and cramps.
Weakness of the heart muscle.
Loss of appetite.
Poor weight gain.
Rapid breathing.
The saliva in the mouth breaks down the polysaccharides which are present in the carbohydrates. The polysaccharidesare further broken down in to disaccharides in the stomach by the action of pancreatic amylase. The enzymes lactase, maltase and sucrose are released by the small intestine which breaks down the disaccharides into monosaccharide. The undigested carbohydrates reach the large intestine and are broken down into smaller parts by the intestinal bacteria.
Fats are made up of lipid chains. The lingual lipase breaks down the short chain of lipids into diglycerides. The small intestine contains some fat which helps in the stimulation of the lipase release from the pancreas along with liver releasing bile. These two act on the diglycerides and dissolve them into fatty acids.
Protein goes into the stomach and gets acted on by pepsin which breaks it down into smaller parts. It further moves into the duodenum where the enzymes chymotrypsin and trypsin are released from the pancreas and break the protein into further smaller parts.
A – substrate entering the active site of enzyme.
B – enzyme-substrate complex.
C – enzyme-products complex.
D – Products leaving active site.
Hydrochloric acid.
Pepsinogen can only unfold and cleave itself in the autocatalysis only in the presence of an acidic environment which is generated by hydrochloric acid and hence, generates pepsin which is the active form of the enzyme which helps to break down proteins. If hydrochloric acid is not generated the breakdown of protein will not occur.
The condition of the stomach when it is unable to form hydrochloric acid is known as hypochlorhydria. The treatments are:
Taking supplements for acid for a short period of time.
Intake of ascorbic acid at high doses preferably during mealtime.
Taking betaine hydrochloride with food.
Bowman’s capsule
Glomerulus
Proximal tubule
Distal tubule
Collecting duct
Loop of Henle
The active transport of glucose takes place during digestion. The carbohydrates are broken down first into sugars and then into glucose. Through active transport, the villi absorb the glucose and passes into the bloodstream to the body.
The active transport of glucose takes place in the proximal and distal convoluted tubules of the nephron.
Long reflexes or feedforward reflexes to the digestive system send information to the brain through the sensory neuron. This reflex induces reactions to events which trigger danger or hunger in the gastrointestinal tract. Gastrointestinal response can also be triggered due to emotional responses.
The enteric system itself can act on the sensory information of the digestive system. The enterogastric reflex which is a short reflex gets stimulated by the acid which is released either by the stomach or the duodenum and hence, results in inhibiting the release of gastrin which suppresses the secretion of gastric acid along with the gastric motility (Tarkka, 2014).
Peristalsis or the motility of the GI tract is increased by the gastrocolic reflex. Hence, the motility of the colon is raised due to the stretching of the stomach and the presence of the digestion byproducts in the small intestine.
The endocrine system spreads the hormonal messages to the cells by secretion in to the extracellular fluids and blood. A receiver is required to get the message and is more or less similar to a radio broadcast. In order to response, the cells must possess a receptor for the hormone that is being broadcast. Signals are sent to the digestive system via pancreas to fix the time for commencing their functions. It also controls as well as stabilizes the mood, growth and development over a period of time (Rogers, 2012).
The nervous system implies the absolute usage of nerve to nerve control while sending a message (Gray, 2004). The nature is electrical and hence, it is faster. The autonomic nervous system controls the digestive functions such as:
The salivary glands which secrete saliva
Gastrointestinal tract motility or peristalsis so that the food can move down easily
Production of gastric acid in the stomach
Opening and closing of sphincter
The release of hormones from the glands in the system
Storage of energy in the form of fat
In order to survive a stable environment is required by cells. Homeostasis is the process through which living beings can maintain constant levels of pH, temperature, water balance and ions. Negative feedbacks control these mechanisms. This includes the system responding to the changes in the environment through the release of hormones so that a trend in the body, whether high or low, can be reversed and restored to the normal range (Wicker, 2002).
The levels of glucose need to be maintained strictly since it is the source of energy for the cells. Excess of glucose is harmful for the cells whereas too less amount of it can lead to starvation. Homeostasis of glucose is dependent on types of cells, molecules and organs. Several reasons can lead to the fluctuation of the blood glucose levels:
The meal is digested and the liver produces insulin. This leads to raised levels of blood glucose.
Glucose levels get lowered when the sugar gets transported into the cells and gets lost from the body in the form of urine.
Insulin and glucagon are the two pancreatic hormones, antagonistic in nature, which control the level of glucose in the blood. The alpha- and beta- cells of the pancreas contain the glucose transport receptors which detect the presence of glucose in the blood. Beta- cells secrete insulin and hence, respond to the increasing level of glucose in the blood. Insulin instigates the body tissues to take up glucose for energy or to convert into lipids and glycogen so that it can be used as future sources of energy and gets stored up in muscle, liver and fat cells. When the glucose levels are low, glucagon hormone is released by the alpha- cells of the pancreas which triggers the liver and skeletal muscles to produce glucose by breaking down glycogen (Alavez & Lithgow, 2012). It also stimulates the adipose tissue into digesting the lipids into glycerol and fatty acids. It also triggers the liver to produce glucose from the glycerol which is present in blood. All these reactions help to make the concentration of glucose in the bloodstream normal.
Type 1 diabetes
This is an auto-immune disease where there is a malfunction o the auto-immune system of the body and the beta- cells in the pancreas are damaged. Here, the levels of blood glucose remain high since, the production of insulin gets hampered and hence, to maintain homeostasis an external dosage of insulin is required.
Type 2 diabetes
This is the most common form of diabetes in which the body stops responding to insulin. For some time the body can cope up with this by increasing the production of insulin but after sometime the pancreas can no longer produce insulin.
References
AN, K. (2012).Modern Trends in Early Diagnosis of Acute Respiratory Distress Syndrome.J PulmonarRespirat Med, 02(01). https://dx.doi.org/10.4172/2161-105x.1000e104
Haywood, K. (2009). Skeletal system. New York: Marshall Cavendish Benchmark.
Matusiak, D. (2013). Mosby’s Anatomy & Physiology Study and Review Cards. London: Elsevier Health Sciences.
Thibodeau, G., Patton, K., & Anthony, C. (2012).Structure & function of the body. St. Louis, Mo.: Elsevier/Mosby.
Veitch, C. (2012). A balanced diet. Chicago, Ill.: Heinemann Library.
Woodson, J. (2003). Locomotion. New York: G.P. Putnam’s Sons.
Alavez, S., & Lithgow, G. (2012). Pharmacological maintenance of protein homeostasis could postpone age-related disease. Aging Cell, 11(2), 187-191. https://dx.doi.org/10.1111/j.1474-9726.2012.00789.x
Gray, S. (2004). The nervous system. Chanhassen, Minn.: Child’s World.
Rogers, K. (2012). The endocrine system. New York: Britannica Educational Pub. in association with Rosen Educational Services.
Tarkka, I. (1986). Short and long latency reflexes in human muscles following electrical and mechanical stimulation. Oxford: Published for the Scandinavian Physiological Society by Blackwell Scientific Publications.
Wicker, P. (2002). Perioperative Practice: Fundamentals of Homeostasis Perioperative Practice: Fundamentals of Homeostasis. Nursing Standard, 17(7), 28-28. https://dx.doi.org/10.7748/ns2002.10.17.7.28.b74
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